RESUMO
If apoptotic cells are not removed efficiently, they may proceed to the stage of secondary necrosis, which would cause inflammation. Therefore, identification of cause(s) and agent(s) for down-modulating phagocytosis of apoptotic cells would help understand the pathologies. In this study we found that macrophage-mediated phagocytosis of apoptotic cells was suppressed by both soluble and particulate ß-glucan. This suppression was not observed when secondary necrotic cells were used. The adhesion of apoptotic cells to macrophages was not suppressed by soluble ß-glucan, suggesting that soluble ß-glucan suppresses phagocytosis at a post-adhesion step. Experiments involving PKC inhibitors suggested that PKC-ßII is required for phagocytosis of apoptotic cells but not secondary necrotic ones by macrophages. Translocation of GFP-PKC-ßII from the cytoplasm to membranes occurred upon interaction with apoptotic cells but not secondary necrotic ones. Such translocation was inhibited by soluble ß-glucan. Overall, this study suggests that suppression of macrophage-mediated phagocytosis of apoptotic cells by soluble ß-glucan is due to a failure of PKC-ßII translocation.
